title: Origins of adaptive immunity.
abstract: Adaptive immunity, involving distinctive antibody- and cell-mediated responses to specific antigens based on "memory" of previous exposure, is a hallmark of higher vertebrates. It has been argued that adaptive immunity arose rapidly, as articulated in the "big bang theory" surrounding its origins, which stresses the importance of coincident whole-genome duplications. Through a close examination of the key molecules and molecular processes underpinning adaptive immunity, this review suggests a less-extreme model, in which adaptive immunity emerged as part of longer evolutionary journey. Clearly, whole-genome duplications provided additional raw genetic materials that were vital to the emergence of adaptive immunity, but a variety of other genetic events were also required to generate some of the key molecules, whereas others were preexisting and simply co-opted into adaptive immunity.
authors.affiliation: School of Medicine & Strategic Research Centre in Molecular and Medical Research, Deakin University, Waurn Ponds, Victoria, Australia.
authors.forename: Clifford
authors.initials: C
authors.lastname: Liongue
authors.forename: Liza B
authors.initials: LB
authors.lastname: John
authors.forename: Alister
authors.initials: A
authors.lastname: Ward
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D019143:Evolution, Molecular; D016678:Genome; D006801:Humans; D010802:Phylogeny